. >> hugh they can justify raising taxes on the middle class has been buried the last four years. how in lord's name can they justify raising their taxes. >> the romney campaign seized on that comment. arguing the president's policies have hurt the middle class. taking a breather from his preparations outside las vegas today. he visited the hoover dam. >> it's spectacular and i've never seen it before. >> reporter: aides say he's been calling his family to unwind each night. surrogates on both sides today acknowledge the debate will be a pivotal moment. >> i think it's important for viewers to get a chance to do comparison shopping. seeing the two candidates face to face, head to head. >> this cannot be about decemberibledecembe decibles. it has to be about details, particularly for governor romney. >> reporter: romney says he doesn't like formal debate preps, says it feels too artificial. instead, opting for more casual sessions. aides are coaching romney not to get visibly irritated if his opponent gets under his skin. something rob portman has been able to do in practice sessio